Hostname: page-component-cd9895bd7-mkpzs Total loading time: 0 Render date: 2024-12-24T01:58:01.706Z Has data issue: false hasContentIssue false
  • English
  • Français

Oxygen Isotope Changes During Mica Alteration

Published online by Cambridge University Press:  02 April 2024

Sridhar Komarneni ,
Marion L. Jackson  and
David R. Cole
Sridhar Komarneni
Affiliation:
Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802
Marion L. Jackson
Affiliation:
Department of Soil Science, University of Wisconsin, Madison, Wisconsin 53706
David R. Cole
Affiliation:
Chemistry Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Oxygen isotope analyses (δO18) of micas that were artificially depleted in K+ indicate little or no isotope exchange during the transformation. The oxidation of iron in K-depleted, iron-rich micas by H2O2 treatment resulted in 1.6 to 4.6% decrease in SO18 due to the fact that the equilibrium fractionation factor is less than the initial difference between the starting δO18 of the fluid and micas. The oxygen isotope ratio of a saponite formed by the weathering of phlogopite showed a 9.7% increase in δO18 due to authigenic recrystallization. These results suggest that oxygen isotope ratios can be used to determine the nature of chemical transformation during the weathering of mica to vermiculite and/or smectite.

Резюме

Резюме

Изотопный анализ кислорода (δO18) в образцах слюды, содержание K+ в которых было искуственно уменьшено, указывают на незначительный или нулевой изотопный обмен во время превращения. Результатом окисления железа в К-обедненных, обогащенных железом слюдах, при помощи обработки перекисью было уменьшение δO18 на 1,6 до 4,6‰ Это было вызвано тем, что величина равновесного коэффициента разделения была меньше, чем разница начальных значений δO18 для течи и слюд. Отношение изотопов кислорода для сапонита, образованного путем выветривания флогопита показало 9,7% увеличение значения δO18, вызванное аутогенной рекристаллизацией. Эти результаты указывают на то, что отношения изотопов кислорода могут быть использованы для определения природы химического превращения во время выветривания слюды и формирования вермикулита и/или смектита. [E.G.]

Resümee

Resümee

Sauerstoffisotopen-Analysen (δO18) von Glimmern, denen K+ künstlich entzogen wurde, zeigen geringen oder gar keinen Isotopenaustausch während der Umwandlung. Die Oxidation von Eisen in K+-verarmten, Eisen-reichen Glimmern durch H2O2-Behandlung führte zu einer Abnahme von 1,6 bis 4,6% bei δO18, aufgrund der Tatsache, daß der Gleichgewichtsfraktionierungsfaktor kleiner ist als der ursprüngliche Unterschied zwischen dem Ausgangswert δO18 der Flüssigkeit und dem der Glimmer. Das Sauer-stoffisotopenverhältnis eines Saponits, der durch Verwitterung von Phlogopit gebildet wurde, zeigte eine Zunahme von 9,7% des δO18-Wertes aufgrund autigener Rekristallisation. Diese Ergebnisse deuten darauf hin, daß die Sauerstoffisotopenverhältnisse dazu verwendet werden können, die Art der chemischen Umwandlung während der Verwitterung von Glimmer zu Vermiculit und/oder Smektit zu bestimmen. [U.W.]

Résumé

Résumé

Des analyses d'isotope oxygène (δO18) de micas dont on a artificiellement retiré K+ ont indiqué peu ou pas d’échange d'isotopes pendant la transformation. L'oxidation du fer dans des micas riches en fer, privés de K par traitement H2O a resulté en une diminution d’1,6 à 4,6% de δO18 à cause du fait que le facteur de fractionation d’équilibre est plus petit que la différence initiale entre le δO18 de départ du fluide et des micas. La proportion d'isotope oxygène d'une saponite formée par l'altération d'une phlogopite a montré une augmentation de 9,7% de δO18 à cause de la recristallisation authigénique. Ces résultats suggèrent que les proportions d'isotope oxygène peuvent être utilisées pour déterminer la nature de la transformation chimique pendant l'altération du mica en vermiculite et/ou en smectite. [D.J.]

Keywords

MicaOxygen isotopesPotassiumRecrystallizationSaponiteWeathering
Type
Research Article
Information
Clays and Clay Minerals , Volume 33 , Issue 3 , June 1985 , pp. 214 - 218
Copyright
Copyright © 1985, The Clay Minerals Society

References

Clayton, R. N. and Mayeda, T. K., 1963 The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis Geochim. Cosmochim. Acta 27 43–52.CrossRefGoogle Scholar
Craig, H., 1961 Standard for reporting concentrations of deuterium and oxygen 18 in natural waters Science 133 1833–1834.CrossRefGoogle ScholarPubMed
Hoefs, J., 1980 Stable Isotope Geochemistry 2nd Berlin Springer-Verlag.CrossRefGoogle Scholar
Jackson, M. L., 1956 Soil Chemical Analysis—Advanced Course Madison, Wisconsin Department of Soil Science, University of Wisconsin.Google Scholar
Jackson, M. L., Hseung, Y., Corey, R. B., Evans, E. J. and Vanden Heuvel, R. C., 1952 Weathering sequence of clay-size minerals in soils and sediments: II. Chemical weathering of layer silicates Soil Sci. Soc. Amer. Proc 16 3–6.CrossRefGoogle Scholar
Jackson, M. L. and Sridhar, K., 1974 Scanning electron microscopic and X-ray diffraction study of natural weathering of phlogopite through vermiculite to saponite Soil Sci. Soc. Amer. Proc 38 843–847.CrossRefGoogle Scholar
Lawrence, J. R., Taylor, M. P. Jr., 1971 Deuterium and oxygen-18 correlation: clay minerals and hydroxides in Quaternary soils compared to meteoric waters Geochim. Cosmochim. Acta 35 993–1003.CrossRefGoogle Scholar
Lawrence, J. R., Taylor, M. P. Jr., 1972 Hydrogen and oxygen isotope systematics in weathering profiles Geochim. Cosmochim. Acta 36 1377–1393.CrossRefGoogle Scholar
Roth, C. B., Jackson, M. L. and Syers, J. K., 1969 Deferration effect on structural ferrous-ferric iron ratio and CEC of vermiculites and soils Clays & Clay Minerals 17 253–264.CrossRefGoogle Scholar
Savin, S. M. and Epstein, S., 1970 The oxygen and hydrogen isotope geochemistry of ocean sediments and shales Geochim. Cosmochim. Acta 34 43–63.CrossRefGoogle Scholar
Scott, A. D., Ismail, F. T. and Locatis, R. R., 1972 Changes in interlayer potassium exchangeability induced by heating micas Proc. Int. Clay Conf., Madrid, 1972 2 467–479.Google Scholar
Scott, A. D., Smith, S. J. and Bailey, S. W., 1966 Susceptibility of interlayer potassium in micas to exchange with sodium Clays and Clay Minerals New York Pergamon Press 69–81.CrossRefGoogle Scholar
Sridhar, K. and Jackson, M. L., 1974 Layer charge decrease by tetrahedral cation removal and silicon incorporation during natural weathering of phlogopite to saponite Soil Sci. Soc. Amer. Proc 38 847–850.CrossRefGoogle Scholar
Sridhar, K., Jackson, M. L. and Syers, J. K., 1972 Cation and layer charge effects on blister-like osmotic swelling of micaceous vermiculite Amer. Mineral 57 1832–1848.Google Scholar
Taylor, H. P. Jr. and Epstein, S., 1962 The relationship between O18/O16 ratios in coexisting minerals of igneous and metamorphic rocks Geol. Soc. Amer. Bull 73 461–480.CrossRefGoogle Scholar
Veith, J. A. and Jackson, M. L., 1974 Iron oxidation and reduction effects on structural hydroxyl and layer charge in aqueous suspension of micaceous vermiculites Clays & Clay Minerals 22 345–353.CrossRefGoogle Scholar